Workers in southern China, who say they were assembling Apple laptops and iPhones, have become seriously ill after using a dangerous chemical. The Number Five People's Hospital in Suzhou has been treating workers who breathed in vapours from the chemical n-hexane. According to the workers, the chemical was being used in the production of Apple products and has left them unable to walk. The ABC's Foreign Correspondent snuck into the Number Five People's Hospital to visit a group of women who were working in a very small, badly ventilated factory. They say they were using n-hexane to glue and polish the logos on Apple products - at least they assumed they were not fakes. One had kept some of the logos they were using to prove that they were working on Apple products and showed them to the ABC. After breathing in the chemical's vapours, they became dizzy and numb and eventually they could not walk. "At first the symptoms were pretty obvious. My hands were numb. I could hardly walk or run," one woman told the ABC. "I think they knew it was poisonous to human bodies but if they had used another chemical our output would not have increased," another woman said. "By using n-hexane, it was much more efficient". The women have now been in hospital for more than half a year. The workers' boss, Zhong Jianxiang, was not available to be interviewed. Apple, meanwhile, would not confirm it had sourced products from companies based in China, but said it had tightened its requirements regarding workplace safety at its suppliers.'It's very painful' Workers in much bigger factories have also reported similar stories. The large Taiwanese-owned operation Wintek has 20,000 employees, and its main client is Apple. "Our company mainly produces the touch screens for mobile phones. Our main client is Apple," one worker said. Wintek has also been using n-hexane and, after breathing in the chemical, more than 60 workers had to be hospitalised. "I am back at work but my symptoms are still with me," one worker said. "My legs still hurt. This will accompany me for the rest of my life. It's very painful." Wintek has paid its workers' hospital bills and said it had removed n-hexane from its production lines.